TwinKey

One key, both runtimes. TwinKey makes a Portaldot SS58 wallet sign for Solidity dApps on Portaldot V3 — the same key that holds your POT pays gas, calls contracts, and reads state over a standard EVM interface. No second wallet, no seed import, no bridging between two identities.

Status: in build (Portaldot Hacker House 2026, track Modular Cloud & Middleware). Live chain facts, including the ones this product depends on, are in docs/VERIFIED-FACTS.md — every one reproducible with a curl.

The screenshot above is the deployed app: both faces of one account resolved from the chain, live contract state over eth_call, a real write, decoded revive.ContractEmitted events, and the Rust verifier's verdict for block 90995.

Live demo: https://twinkey.vercel.app Verifier: https://twinkey-verifier.onrender.com/ready (Rust, Render — free tier, so the first request after an idle spell takes ~30–60 s to cold start). /ready is the deep check (both upstream RPCs, head block); /health is liveness only and answers from memory, because Render kills the instance when its own probe takes more than 5 s

The deployed instance runs the write path with a dedicated throwaway demo account (5He7dvDWyMs7DAiAVBsfczFZPEKVa5tAQwLQjNTSq3beUAHZ → 0xfd2d914e…62e7), funded with 5 tPOT and rate limited to 3 writes per minute per IP, so the write button works for a judge without an extension. It is deliberately not the project key. Connect your own wallet to sign as yourself.

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The problem

Portaldot Network V3 gives every account two faces: a native AccountId32 (SS58, prefix 42, the one every Portaldot/polkadot.js wallet produces) and an H160 address on the EVM side. The two are linked by the runtime — ReviveApi.address(account_id32) returns the H160 — but nothing in the ecosystem exposes that link to users or to dApps.

The consequence, today, on the live testnet:

• A Portaldot user opens any Solidity dApp and is told to install a different wallet with a different seed phrase. Their POT cannot sign an EVM transaction.
• A dApp built with viem / wagmi / ethers cannot talk to a Portaldot wallet at all: those libraries expect an EOA that signs eth_transact-style transactions, while the account that actually holds the funds is an sr25519 Substrate account.
• The runtime does allow a native account to drive contracts (revive.call, revive.instantiate_with_code), and the Portaldot team's own guide documents it as a manual four-step procedure in the node console: generate calldata, dry-run through reviveApi.call to obtain weight_limit and storage_deposit_limit, then submit Revive.call from the Extrinsics tab. Nothing in the ecosystem implements that flow — no wallet, no SDK, no dApp.
• In the other direction, the EVM write path that MetaMask/Remix users are told to use does not accept transactions from an external EOA on the current testnet build (every type, fee and gas combination returns Invalid Transaction; revive.originalAccount is unset for the EOA while its balance is displayed). Reads, eth_call and eth_estimateGas work normally. Full reproduction: docs/FINDINGS.md.

So the chain's headline feature — EVM compatibility — is unusable by the people the chain already has. TwinKey closes that gap.

What TwinKey is

One key, two endpoints: reads go to the EVM RPC at latest, writes go to the Substrate RPC as revive.call extrinsics signed by the SS58 key, and a separate Rust process checks that both sides agree. The editable source of that diagram is docs/diagrams/architecture.html — open it in a browser, no build step.

1. A signer bridge. Connect the Substrate wallet you already have (Portaldot extension, polkadot.js extension, or any injected SS58 signer). TwinKey resolves your H160 through the chain's own runtime API, shows both identities as one account, and submits contract calls as native revive.call extrinsics signed by your sr25519 key.
2. An EIP-1193-shaped provider. The same capability as a drop-in provider (window.ethereum-shaped) so existing EVM tooling — viem, wagmi, plain ethers snippets — works against a Substrate signer with no rewrite. The dApp developer changes one line.
3. A parity receipt. For every call, TwinKey can execute the same input through both paths (native revive.call and EVM eth_transact / eth_call) and have an independent verifier assert that post-state, events, and value accounting agree — including across the 14-decimal native / 18-decimal EVM denomination split. This is the proof that the dual runtime is one runtime, and it is what turns a wallet adapter into infrastructure.

Who it is for

• Portaldot users with an SS58 wallet who want to use Solidity dApps without a second identity.
• dApp developers on Portaldot V3 who want the wallet base that already exists, instead of asking new users to install MetaMask and buy gas twice.
• The next chain running pallet-revive — the same adapter is not Portaldot-specific: it works against any pallet-revive runtime that exposes the same runtime API.

Why now

Portaldot V3 (runtime portaldot-v3 v3002) is the first Portaldot runtime with pallet-revive alongside pallet-contracts, and the EVM endpoint has been public since October 2026. The chain has issuance, validators and a live testnet, and — at the time of writing — no deployed contracts and no wallet path from the native side. The adapter has to exist before the first dApp can onboard its first user.

Core user experience

1. Land on the app. Connect the Substrate wallet you already have.
2. Your account appears once, with both faces: 5DM…Bko9C7 and 0xe70f…d934, with the derivation fetched live from the chain (not guessed, not truncated).
3. Pick a contract, call a function, sign once in your existing wallet. TwinKey encodes the call, submits it, tracks the receipt, decodes the events.
4. Flip to the parity pane: the same call through the EVM path, with the verifier's verdict.

Architecture

[Substrate signer]  ──sign revive.call──▶  [TwinKey app]  ──▶ [Substrate RPC] ──▶ pallet-revive
        │                                        │                                     │
        │  ReviveApi.address  ◀── H160 ──        │  viem/EIP-1193 shim                 │ state+events
        ▼                                        ▼                                     ▼
   one account                            [Rust verifier]  ◀── eth-rpc / Substrate RPC ──
                                          /verify/:tx, /parity/:tx

• Web app: Next.js (App Router) + TypeScript + Tailwind, deployed on Vercel.
• Signer + chain access: @polkadot/api, @polkadot/extension-dapp, viem for encoding.
• Verifier: Rust (Axum + tokio + subxt) — reads the chain independently of the browser and returns a verdict a judge can curl.

Repository layout

app/        Next.js front end + the EIP-1193 provider shim
agent/      Rust verifier service (/verify/:tx, /parity/:tx)
tooling/    Node scripts used during development (inspect revive extrinsics, deploy, parity runs)
contracts/  Solidity contracts used for the demo and the parity harness
docs/       VERIFIED-FACTS.md (chain facts with the commands that produced them), notes

Running it

# 1. the app (Next.js) — provider shim + console + decoded EVM event feed
cd app
npm install
npm run dev                       # http://localhost:3000
# optional: enable the in-app demo write with a testnet key file
#   PORTALDOT_KEY=~/.hermes/keys/portaldot-testnet.json npm run dev

# 2. the end-to-end proof: drives the provider like viem would and prints a verdict
npx tsx scripts/e2e-provider.ts 2077

# 3. the Rust verifier (independent of the browser)
cd ../agent
cargo run --release               # http://localhost:8088/verify/block/90990

Exact commands and their output are in docs/BUILD-LOG.md.

Verification — what is real, what is not

Claim	State
Portaldot V3 testnet reachable, chain id, decimals, address mapping	real, verified by curl — docs/VERIFIED-FACTS.md
A registered testnet wallet is funded	real — mapped H160 holds ~401.7 tPOT as of 2026-10-19
Native AccountId32 → H160 mapping via runtime API	real — ReviveApi_address returns 0xe70f…d934 for 5DM…Bko9C7
Contract deployed on the testnet by an ss58 key	real — 0x19d5aa109cbf0d4e0a126f1438ea73b619cb7725, deploy block 90990
Contract called by the same ss58 key, state read back over EVM RPC	real — call block 90995; later calls at 102680, 102716, 102852
An EIP-1193 eth_sendTransaction executes on chain via an ss58 signature	real — app/scripts/e2e-provider.ts 12/12, tx 0x6aac8a66…34f8
eth_getTransactionReceipt returns a receipt with a decoded EVM log	real — ValueSet(caller=0xe70f…d934, value=2077, callCount=4)
eth_estimateGas returns the real cost, not the EVM endpoint's inflated value	real — 50,604,168 vs 417,905,553,159 (8,258×)
Dry-run → exact weight_limit / storage_deposit → execute	real — weightRequired {506041677, 31937} on an earlier call
External EOA can write over the EVM JSON-RPC	no — Invalid Transaction for every tx type; see docs/FINDINGS.md. Reads work.
eth_getLogs returns logs from native-path calls	no — returns [] for our own contract across the full range. The app scans Substrate events and merges receipts instead.
Rust verifier verdict for a call	see agent/ — endpoints and their real output are in the agent README

No mocked behaviour is presented as real here. Anything simulated is labelled as such in the app itself and in the README at submission time.

Security notes

• TwinKey never holds keys and never asks for a seed. All signatures happen inside the user's own wallet extension.
• Native revive.call transfers are signed as Substrate extrinsics, so the trust model is Substrate's, not an EVM relayer's: there is no custodial relayer in the loop.
• The app validates the address mapping against the chain on every connect; it never derives the H160 locally (a local derivation that disagrees with the chain is the failure mode that loses funds).
• Amounts are handled as bigint with an explicit decimal context per side (14 native / 18 EVM) — the single most common way to misreport value on this chain is to assume 18 decimals everywhere.

Limitations / roadmap

• Native path requires a Substrate signer; a wallet that only exposes secp256k1 EVM keys cannot use revive.call (it uses the EVM path instead — supported, but a different flow).
• pallet-revive semantics differ from the EVM in places (PolkaVM); the parity harness exists to make those differences explicit instead of surprising.
• Roadmap: multi-contract batching, ERC-20 precompile support, and a packaged provider (npm i twinkey) that any Portaldot dApp can drop in.

References

• PortaldotV3 Testnet Guide (official, English translation) — https://github.com/ItsCogumellum/portaldot-v3-testnet-guide. Its §3.3.2/§3.4.4 document the manual native-call flow this project automates; its §3.4.2 documents the H160 ↔ SS58 funding trick; demo/04_solidity_demo.py is the reference implementation of the dry-run in Python. TwinKey's tooling/call-dryrun.mjs is the same flow in TypeScript.
• Polkadot SDK pallet_revive — AddressMapper, ContractResult, storage-deposit semantics.

License

MIT. Portaldot Hacker House 2026 submission.